Second, that orbit looks so unstable that he thinks it unlikely that it could have lasted for the 4.5 billion-year history of the solar system.

ECONOMIST: X marks the spot

"If more data confirm Eros is primordial, Eros will be a link between the chondrite meteorites found on Earth and the history of the solar system's formation, " McCoy said.

CNN: Asteroid Eros resembles 'building blocks' of Earth

But most of the history of the solar system--this is why the comet is so important--most of the history of this comet was spent out beyond Neptune, out where Pluto is at the very edge of the solar system, what we call the Kuiper belt.

NPR: Stardust Set to Deliver Comet Samples

"Each meteorite is a time capsule and space probe recording the history of our solar system from 4.5 billion years ago, " said Caroline Smith, curator of meteorites at London's Natural History Museum.

WSJ: Russia Meteor Was Largest in More Than a Century

Ultimately, the new studies offer some surprises, and some confirmations of the coalescing picture scientists have about this early stage of the solar system's history.

MSN: Surprisingly, giant asteroid Vesta covered in hydrogen

Most are transient visitors to the vicinity of earth their orbits are so long that many of those arriving now (such as Hale-Bopp) must have made any previous visit to the inner solar system before the beginning of recorded history.

ECONOMIST: Unbuckling the Kuiper belt

If the moon harbours ice, for example, measuring the amount of it at different depths could enable planetary scientists to work out the rate at which comets smashed into the lunar surface over its history, and that knowledge could then be plugged into models of the formation of the solar system.

ECONOMIST: Divining water

Though Mr Shoemaker's career was diverse, it had a central theme: that some of the main events in the solar system's history were not gradual changes, as scientists once supposed, but sudden, violent catastrophes.

ECONOMIST: Gene Shoemaker